public class GradeEvaluation {
    public static void main(String[] args) {
        int c = 85;
        String grade;
        if (c >= 90 && c <= 100) {
            grade = "A";
        } else if (c >= 70 && c < 90) {
            grade = "B";
        } else if (c >= 60 && c < 70) {
            grade = "C";
        } else if (c >= 0 && c < 60) {
            grade = "D";
        } else {
            grade = "无效成绩";
        }
        System.out.println("成绩 " + c + " 的等级为：" + grade);
    }
}
